Example embodiments are directed to a memory system and a data management method of a flash translation layer thereof.
In general, memory systems include a memory device for storing data and a host for controlling an operation of the memory device. Memory devices are classified into volatile memories and nonvolatile memories. Examples of the volatile memories include DRAMs and SRAMs, and examples of the nonvolatile memories include EEPROMs, FRAMs, PRAMs, MRAM, and flash memories.
The volatile memories lose data stored therein when power supply thereto is interrupted, whereas the nonvolatile memories retain data stored therein even when power supply thereto is interrupted. Among the nonvolatile memories, flash memories are widely used as data storage media because of their high program speed, low power consumption and high data storage capacity.
Memory devices requiring high integration may not always be reliable due to the restrictions in a fabrication process. While the malfunction and yield degradation due to high integration of memory devices may be overcome, it is not easy for a user to determine memory device malfunctions when a memory device is installed and being used in a memory system.
In general, high-capacity storage devices such as flash memory cards and solid state disks (SSDs) are configured to include a plurality of flash memory chips. Reserved replacement blocks serve to replace the memory blocks that malfunction due to program/erase failures. However, no such replacement service is available for any further malfunctioning memory blocks once all the replacement blocks have been occupied.
Semiconductor memory devices store data, which can then be read therefrom. The semiconductor memory devices are classified into random-access memories (RAMs) and read-only memories (ROMs). RAMs are classified as volatile memories since they lose data stored therein when power supply is interrupted. ROMs are classified as nonvolatile memories since they retain data even after power interruption.
A flash memory device is a nonvolatile memory device used in portable electronic devices such as digital cameras, MP3 players, mobile phones and PDAs because the flash memory consumes low power and has high circuit integration. When flash memories are used in portable electronic devices, the reliability and lifetime of the portable electronic devices depend on the reliability and lifetime of the flash memories. Thus, it is important to improve the reliability and lifetime of the flash memories.
Semiconductor memory devices store data, which can then be read therefrom. The semiconductor memory devices are classified into volatile memory devices and nonvolatile memory devices. When power supply is interrupted, the volatile memory devices lose data stored therein, examples of which include SRAMs, DRAMs, and SDRAMs. However, even when power supply is interrupted, the nonvolatile memory devices retain data stored therein, examples of which include ROMs, PROMs, EPROMs, EEPROMs, and flash memories, PRAMs, MRAMs, and FRAMs. The flash memories are classified into NAND flash memories and NOR flash memories.
Computing systems use a semiconductor disk device, instead of a hard disk device, as a storage medium. In terms of reliability and speed, the semiconductor disk devices are superior to hard disk devices using rotating disks.